1. Field of the Invention
The present invention generally relates to the art of rotating and holding workpieces, such as plastic bottles and the like, for conveyance or transfer through a treatment zone or from one location to another. More particularly, this invention is drawn to a novel holding device that concurrently rotates the work piece while it is transported from one location to another, and further, is adaptable for use in a variety of work environments requiring workpiece rotation, e.g., automated bottle spraying, washing, sanitizing and bottle labelling systems and the like.
2. Discussion of Prior Art
The manufacture of returnable and refillable bottles has become widespread in both the glass and plastic bottling industries. Many countries have mandated their use in an effort to conserve energy and to keep raw material consumption to a minimum. Furthermore, commercially viable, refillable bottles and containers not only conserve energy, but help to reduce land-fill and recycling problems usually associated with disposable type plastic and glass bottles and containers. One industry in particular where the desirability of utilizing reusable and refillable plastic bottles is increasing, is in the soft drink beverage bottling industry.
To be commercially viable as a refillable bottle for soft drink beverages, the plastic bottle must retain its aesthetic and functional qualities over a minimum of ten and preferably over twenty cycles or "trips" in its lifetime. A typical cycle that a returnable/refillable plastic bottle goes through has been described in numerous patents and technical articles. For instance, U.S. Pat. No. 4,725,464 to Collette, incorporated by reference herein, describes a cycle as comprising: 1) an empty caustic wash followed by 2) contaminant inspection and product filling/capping, 3) warehouse storage, 4) distribution to wholesale and retail locations, and 5) purchase, use, and empty storage by the consumer followed by eventual return to the bottler. Presently, plastic beverage bottles made of polyesters, such as polyethylene terephthalate (PET) and copolymers thereof, acrylonitrile, and polycarbonate have the requisite physical and aesthetic qualities most desirable for producing refillable plastic containers. As is well known in the art, PET offers the best balance of properties and, cost and performance ratios.
While the plastic bottling industry has made great strides in obviating the problems associated with the production of commercially viable returnable and refillable plastic bottles in terms of maintaining the chemical and structural integrity of the plastic bottle after repeated caustic washing, problems still arise during the caustic wash process of the typical cycle described above. For instance, many bottles or containers are subject to excessive scuffing because of the way they are handled in the washing machines of the prior art. In addition, the temperature of washing fluids and rough handling may also be a source of bottle stress induced cracking.
Prior art automatic and semi-automatic bottle washing apparatuses, such as the straight line systems described in U.S. Pat. Nos. 4,080,974 and 4,125,120 and the automated rotary systems described in U.S. Pat. Nos. 3,226,757, 3,534,749, and 5,135,014 each provide for the exterior and/or interior washing of the bottle while it is fixed in one position or while the bottle is moving from one treatment zone to another. A problem associated with these current automated spray washing apparatuses is that many bottles are subject to stress crack failure by reason of the combination of the high temperature wash solution, the caustic nature of the solution and the way they are handled. For instance, the automated in-line and rotary bottle washing systems mentioned above currently provide mechanisms for holding or suspending containers, for example, by cradle (U.S. Pat. No. 4,080,974), basket (U.S. Pat. No. 4,154,624), carriage (U.S. Pat. No. 4,461,054), or by fixed mounting means (U.S. Pat. No. 3,534,749), as the bottles are being conveyed or transferred through the wash treatment. Both scuffing and stress crack failure occur in these mechanisms as the bottles rub or brush against each other or against a holder or other surface while in transit.
In view of the above-mentioned limitations and disadvantages of the bottle handling devices found in current automated bottle washers, there is accordingly a need to provide an apparatus for holding and rotating bottles or containers in a manner that minimizes the stress in the neck and shoulder regions and that does not require any sort of retaining or locking means.